JP3809293B2 - Ultrasonic excitation device and ultrasonic cleaning device provided with the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic exciter used for cleaning, for example, silicon wafers for industrial use, and more particularly to an ultrasonic exciter having a drive frequency of 200 kHz or more and an ultrasonic cleaner provided with the ultrasonic exciter.
[0002]
[Prior art]
The ultrasonic cleaning apparatus using such a high frequency band is capable of removing submicron particles (particulates), is free of damage to the cleaning object because of no cavitation, and has a short wavelength. Since ultra-precise cleaning is possible, such as the fact that there is no effect of standing waves and a spotless cleaning effect has been developed and put into practical use.
[0003]
As a conventional ultrasonic cleaning apparatus of this type, for example, there is a cleaning tank type shown in FIG. The ultrasonic cleaning apparatus shown in FIG. 6 is disclosed in JP-A-10-94756.
[0004]
FIG. 6 is a side view including a partial cross-section illustrating a conventional ultrasonic cleaning apparatus, and FIG. 7 is a perspective view illustrating a conventional ultrasonic vibration generator included in the conventional ultrasonic cleaning apparatus. Hereinafter, a conventional ultrasonic cleaning apparatus (including an ultrasonic excitation apparatus) will be described with reference to FIGS. 6 and 7.
[0005]
As shown in FIG. 6, a conventional ultrasonic cleaning apparatus 110 is attached to a bottom of the processing tank 102 that stores, for example, pure water 101 as a cleaning fluid and stores an object to be cleaned. And an ultrasonic vibration generator 103.
[0006]
As shown in FIG. 7, the ultrasonic vibration generating unit 103 includes a substantially rectangular parallelepiped waveguide 105 and a transducer formed in a rectangular plate shape and coupled to the waveguide 105 with an adhesive or the like. 104, and is inserted through an opening 102a formed at the bottom of the processing bath 102 in a state where the waveguide 105 side is in contact with the liquid. A flange portion 105 a is formed on the entire waveguide 105, and a packing 106 is interposed between the flange portion 105 a and the bottom portion of the processing tank 102, so that the waveguide body 105 is closely fixed to the bottom portion of the processing tank 102. Has been. The packing 106 functions as a liquid-tight and vibration-absorbing member.
[0007]
The vibrator 104 is composed of a PZT (piezoelectric: piezoelectric) element or the like. When a voltage having a predetermined driving frequency is applied by an oscillator 107 (see FIG. 6), ultrasonic vibration of this frequency is generated. The drive frequency is set extremely high, for example, 1 MHz. The ultrasonic vibration generating unit 103 including the vibrator 104 and the waveguide 105 and the oscillator 107 constitute an ultrasonic excitation device.
[0008]
The waveguide 105 is made of, for example, duralumin, and has a thickness H, that is, a dimension in the traveling direction of the ultrasonic vibration generated from the vibrator 104, which is an approximate integer of a half wavelength (λ / 2) of the ultrasonic vibration. Double, ideally just an integral multiple, and the resonance length. The waveguide body 105 resonates with the ultrasonic vibration generated by the vibrator 104, introduces ultrasonic vibration into the pure water 101 and excites it, and is immersed in the pure water 101. An object such as a silicon wafer (not shown) is cleaned.
[0009]
Here, the half wavelength (λ / 2) is calculated as follows.
λ / 2 = C / 2f
However,
λ: one wavelength C: sound speed of duralumin = 5.15 × 10 ⁵ cm
f: Frequency = 10 ⁶ Hz
Therefore, λ / 2 = 2.6 mm.
[0010]
In the conventional waveguide 105, the thickness H is set to 53 mm. That is, it is about 20 times the half wavelength λ / 2 (about 2.6 mm), and the thickness H is set large. Therefore, the waveguide 105 has a relatively large acoustic impedance, the pure water 101 existing as an external load above the waveguide 105 is insufficient for some reason, and the liquid level 101a is not guided. Even when the wave body 105 is lowered below the upper surface of the wave body 105, the acoustic impedance of the entire device is lowered, the vibration of the vibrator 104 is increased, the effective output is increased, and the effective output is increased to generate heat. Can be suppressed. Specifically, the acoustic impedance of the waveguide 105 is expressed by the following formula: Rma ₁ <Rma ₂ <Rma ₃ (1)
However,
Rma ₁ : acoustic impedance of the vibrator 104 Rma ₂ : acoustic impedance of the waveguide 105 Rma ₃ : set in a state satisfying the acoustic impedance of the pure water 101.
[0011]
The effect of suppressing the increase in effective output is apparent from the following equation.
^{Pa = Va 2 / Rma ··· (} 2)
Rma = Rma ₁ + Rma ₂ + Rma ₃ (3)
However,
Pa: Effective output Va: Applied voltage (constant)
Rma: acoustic impedance of the entire cleaning apparatus (including pure water 101)
That is, even if the pure water 101 decreases and the value of the acoustic impedance Rma ₃ becomes almost zero, the waveguide 105 has the acoustic impedance Rma ₂ of a required magnitude, so that the effective output Pa is large. It has a configuration that does not increase.
[0013]
The flange portion 105 a is formed with a pair of through holes 105 b along the longitudinal direction of the waveguide 105 as means for cooling the waveguide 105. A nipple 108a is screwed into one end of the through hole 105b, and a nipple 108b is screwed into the other end.
[0014]
Then, for example, pure water is supplied as cooling fluid into the through-hole 105b through the tube 109a connected to the nipple 108a, and the pure water as cooling fluid is supplied through the tube 109b connected to the nipple 108b. Is configured to be discharged.
[0015]
[Problems to be solved by the invention]
The conventional ultrasonic cleaning apparatus 110 has the following advantages.
[0016]
(1) The thickness H of the waveguide 105 is set large, and the waveguide 105 has a relatively large acoustic impedance. Therefore, even when the pure water 101 existing as an external load above the waveguide 105 is insufficient for some reason, and the liquid level 101a is lowered below the upper surface of the waveguide 105, the empty water is blown away. The state, that is, the acoustic impedance of the apparatus as a whole decreases and the vibration of the vibrator 104 increases, and the effective output increases to suppress heat generation. That is, the adhesive that fixes the vibrator 104 to the waveguide 105 can be prevented from degrading and peeling, and the vibrator 104 itself can be prevented from being cracked by heat. Yes.
[0017]
(2) As the cooling means for the waveguide body 105, a pair of through holes 105b are formed in the flange portion 105a, and a structure for supplying a cooling fluid such as pure water is provided. Since heat that adversely affects the heat can be removed as much as possible, the pair of through-holes 105b are provided in the flange portion 105a formed so as to protrude from the waveguide 105. The configuration is such that the ultrasonic vibration conducted by the waveguide 105 is not adversely affected such as attenuation.
[0018]
(3) Maintenance is extremely easy because there is no need to provide an interlocking facility consisting of a sensor or the like in order to prevent emptying.
[0019]
On the other hand, in recent years, in order to improve the efficiency of the space where various apparatuses are installed, the apparatus itself is required to be downsized. From this point, further downsizing of the apparatus such as the ultrasonic cleaning apparatus 110 has been studied. ing.
[0020]
However, in the conventional ultrasonic cleaning device 110, the flange portion 105a is formed over the entire circumference of the waveguide 105 constituting the ultrasonic excitation device. Since the flange portion 105 a is formed so as to protrude from the waveguide body 105, it has an advantage as a portion where the cooling means is provided, while the waveguide body 105 and the processing tank 102 are attached. A site | part becomes large and there exists a tendency for the said ultrasonic cleaning apparatus 110 whole to enlarge.
[0021]
The present invention has been made in view of the above points, and even when the cleaning fluid is reduced, an increase in effective output can be reliably suppressed, and an adverse effect such as attenuation can be exerted on the transmitted ultrasonic vibration. It is an object of the present invention to provide an ultrasonic excitation device that can be reduced in size without being given. It is another object of the present invention to provide an ultrasonic cleaning apparatus that includes the ultrasonic excitation device and can achieve downsizing of the entire device.
[0022]
[Means for Solving the Problems]
An ultrasonic excitation device according to the present invention includes a vibrator that generates ultrasonic vibration of 200 kHz or more, a waveguide that is coupled to the vibrator and guides the ultrasonic vibration to an external load, and cools the waveguide. An ultrasonic excitation device having a cooling means, wherein the cooling means has a cavity formed inside the waveguide and into which a cooling fluid flows, and the cavity is configured to transmit the ultrasonic vibration. The dimension in the traveling direction is an integral multiple of a half wavelength of the ultrasonic vibration based on the sound velocity of the cooling fluid, and the size from the upper surface of the waveguide having the vibrator to the upper end of the cavity portion And the size from the lower end of the cavity to the bottom surface facing the top surface of the waveguide is an integral multiple of a half wavelength of the ultrasonic vibration based on the sound velocity of the material of the waveguide. is there.
[0023]
The hollow portion has a rectangular parallelepiped shape or a cubic shape, and is formed in parallel to the vibrator in two directions perpendicular to the traveling direction of the ultrasonic vibration.
[0024]
The outer peripheral surface of the waveguide is flush.
[0025]
The waveguide is made of one material selected from duralumin, stainless steel, quartz, aluminum, aluminum alloy, tantalum, and titanium.
[0026]
Further, the waveguide has a size that is an integral multiple of a half wavelength of the ultrasonic vibration based on a sound speed of a material of the waveguide, in the dimension in the traveling direction of the ultrasonic vibration, When the acoustic impedances of the waveguide and the external load are Rma ₁ , Rma ₂ and Rma ₃ , respectively, the following formula Rma ₁ <Rma ₂ <Rma ₃ is satisfied.
[0027]
The ultrasonic excitation device of the present invention has a sealed case surrounding the vibrator.
[0028]
Further, the ultrasonic cleaning apparatus of the present invention is an ultrasonic cleaning apparatus comprising a treatment tank for storing a cleaning fluid and an ultrasonic excitation device for exciting the cleaning fluid, wherein the ultrasonic excitation device is A vibrator that generates ultrasonic vibrations of 200 kHz or higher, a waveguide that is coupled to the vibrator and guides the ultrasonic vibrations to the cleaning fluid, and a cooling unit that cools the waveguide. The cooling means has a cavity formed inside the waveguide and into which the cooling fluid flows, and the cavity has a dimension in the traveling direction of the ultrasonic vibration that is equal to the sound speed of the cooling fluid. And an integral multiple of a half wavelength of the ultrasonic vibration based on the size, and the size of the waveguide from the upper surface having the vibrator to the upper end of the cavity and the lower end of the cavity to the waveguide The size up to the bottom surface facing the top surface of the waveguide is Wherein based on the sound speed of the wood are those which are an integral multiple of a half wavelength of the ultrasonic vibration.
[0029]
In addition, the ultrasonic cleaning apparatus of the present invention continuously supplies a cleaning fluid, and includes a shower device having a nozzle from which the cleaning fluid is ejected, and an ultrasonic excitation that applies ultrasonic vibration to the cleaning fluid. An ultrasonic cleaning apparatus comprising: a vibrator that generates ultrasonic vibration of 200 kHz or more; and the ultrasonic vibration that is combined with the vibrator to the cleaning fluid. A waveguide for guiding and a cooling means for cooling the waveguide, the cooling means having a cavity formed inside the waveguide and into which a cooling fluid flows, the cavity being The dimension in the traveling direction of the ultrasonic vibration is an integral multiple of a half wavelength of the ultrasonic vibration based on the sound velocity of the cooling fluid, and the cavity from the upper surface of the waveguide having the vibrator The size up to the upper end and the cavity Wherein is from the lower end to the bottom surface facing the top surface of the waveguide size based on the sound speed of the material of the waveguide are those that are integer multiples of a half wavelength of the ultrasonic vibration.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Next, as a first embodiment of the present invention, a cleaning tank type ultrasonic cleaning apparatus (including an ultrasonic excitation apparatus) will be described with reference to FIGS.
[0031]
FIG. 1 is a side view including a partial cross section showing a cleaning tank type ultrasonic cleaning apparatus according to a first embodiment of the present invention, and FIG. 2 is a cleaning tank type according to the first embodiment of the present invention. It is a perspective view which shows the ultrasonic vibration generation part with which an ultrasonic cleaning apparatus is provided.
[0032]
As shown in FIG. 1, the ultrasonic cleaning apparatus 10 a is installed in a processing tank 3 that stores, for example, pure water 1 as a cleaning fluid and accommodates an object to be cleaned, and a bottom of the processing tank 3. And an ultrasonic vibration generator 5.
[0033]
As shown in FIG. 2, the ultrasonic vibration generator 5 includes a waveguide 9 formed in a rectangular parallelepiped shape, a rectangular plate shape, and an adhesive or the like on the waveguide 9 on one side. And the vibrator 7 coupled to each other.
[0034]
As shown in FIG. 1, the ultrasonic vibration generator 5 is inserted into an opening 3a formed at the bottom of the processing tank 3 in a state where the waveguide 9 side is in contact with the liquid, and is flush with the surface. A packing 14 is interposed over the entire circumference between the outer peripheral surface 9a of the waveguide 9 and the inner edge 3b of the opening 3a, and is tightly fixed to the bottom of the processing bath 3.
[0035]
The packing 14 acts as a liquid-tight and vibration-absorbing member, and in this case, the position where the packing 14 is attached, that is, the position where the ultrasonic vibration generator 5 is attached to the bottom of the processing tank 3 is It is located below the cavity 9 c formed in the waveguide 9. Details of the hollow portion 9c will be described later.
[0036]
When a voltage having a predetermined driving frequency is applied by the oscillator 12, the vibrator 7 generates ultrasonic vibration having this frequency. The drive frequency is set to an extremely high value of 200 kHz or more, and is 1 MHz in this embodiment. The ultrasonic vibration generating unit 5 including the vibrator 7 and the waveguide 9, the oscillator 12, and the cooling means for the waveguide 9 described later constitute an ultrasonic excitation device.
[0037]
The waveguide 9 resonates with the ultrasonic vibration generated by the vibrator 7 and acts as a member that guides the ultrasonic vibration to the pure water 1. In this embodiment, the waveguide 9 only transmits the ultrasonic vibration to the pure water 1 and does not have a mechanical amplification function. An amplification function may be provided.
[0038]
The waveguide 9 is made of duralumin or stainless steel (SUS). In this embodiment, duralumin is used as a more preferable example. Similarly to the conventional waveguide 105, the waveguide 9 has a thickness H, that is, the dimension in the traveling direction of the ultrasonic vibration generated from the vibrator 7 is the material of the waveguide 9 In this case, the resonance length is set to approximately an integral multiple of the half wavelength (λ / 2) of the ultrasonic vibration calculated based on the sound velocity of duralumin, ideally just an integral multiple.
[0039]
The thickness H is 53 mm in this embodiment as well as the conventional waveguide 105, and is set to about 20 times the half wavelength λ / 2 (about 2.6 mm). That is, by setting the thickness H large, the waveguide 9 has a relatively large acoustic impedance. In addition, the acoustic impedance of the waveguide 9 is set to a state that specifically satisfies the equation (1), similarly to the conventional waveguide 105.
[0040]
The value of the thickness H is arbitrarily changed according to the relationship with the acoustic impedance of the pure water 1 as an external load existing above the waveguide 9, the magnitude of ultrasonic energy to be transmitted, etc. Is possible. By the way, conventionally, in a high frequency band as in this embodiment, waste of ultrasonic energy, that is, a large amount of heat is generated, and for example, it is commonly recognized that the thickness is limited to 2 to 3 times the half wavelength. It had been.
[0041]
In this embodiment, the waveguide 9 is formed using duralumin as a material. Duralumin has a density (ρ) of about 2.8 g / cm ^3, which is about 1 / compared to iron or stainless steel. It is three. That is, it is a material with very little loss against high-frequency ultrasonic vibrations, and is suitable as a material for the waveguide 9 in which the thickness H is set large. However, it can be applied as a waveguide and can be used as long as the material has a density equivalent to or lower than that of duralumin. For example, quartz, aluminum, aluminum alloy, etc. are used. Also good. For example, tantalum, titanium, or the like can be used to increase the corrosion resistance of the waveguide material in accordance with the cleaning fluid to be used.
[0042]
Further, as shown in FIG. 2, the dimension of the waveguide 9 in a direction perpendicular to the traveling direction of ultrasonic vibration generated from the vibrator 7 (the direction of the thickness H), that is, the length L In this embodiment, the width W and the width W are set to 136 mm and 40 mm, respectively, and are about 52 times and about 15 times the half wavelength λ / 2 (about 2.6 mm), respectively. The length L and the width W are variable according to the size of the object to be cleaned and the size of the processing tank 3.
[0043]
That is, assuming that the length L and the width W use, for example, a relatively low frequency band such as 20 kHz for the driving frequency of the vibrator 7, the waveguide 9 has a Poisson ratio. In order to suppress lateral vibration due to the influence of the above, it is necessary to set the magnitude to λ / 3 or less. In addition, when it is desired to set the length L and the width W large, slits are formed at a pitch of λ / 3 or less, and waveguides having a small size of λ / 3 or less affect each other. It is necessary to take a form that is combined in a state without any. This is to prevent the vibration energy from being consumed in the waveguide itself due to the occurrence of the lateral vibration, and to give the pure water 1 a clean longitudinal vibration not accompanied by the lateral vibration.
[0044]
On the other hand, it has been confirmed from the experiment by the applicant of the present invention that there is no adverse effect of the Poisson's ratio, that is, no occurrence of lateral vibration at an extremely high frequency of 200 kHz or higher, for example, a driving frequency of 1 MHz set in this embodiment. The length L and the width W of the waveguide 9 can theoretically be increased without limitation. Therefore, the waveguide 9 does not need to form a slit, and the length L and the width W can be arbitrarily set to be λ / 3 or more.
[0045]
Next, the cooling means for the waveguide 9 provided in the ultrasonic excitation device of the present invention will be described.
[0046]
As shown in FIGS. 1 and 2, a flat rectangular parallelepiped-shaped cavity is provided at the center of the waveguide 9 in the thickness H direction along the longitudinal direction of the waveguide 9 (the length L direction). The portion 9c penetrates in a state orthogonal to the traveling direction of the ultrasonic vibration generated from the vibrator 7. Said cavity 9c, in the width direction (the width W ₀ direction) and longitudinal (length L direction), are formed in parallel to the said oscillator 7.
[0047]
The hollow portion 9c is closed at both ends by a lid body 9d and a lid body 9e. The lid body 9d and the lid body 9e are made of, for example, duralumin or the like, and are attached to both ends of the hollow portion 9c by welding or the like.
[0048]
In addition, a pair of nipples 28a are screwed into one of the lid bodies 9d, and a pair of nipples 28b are screwed into the other lid body 9e. Tubes 30a communicate with the pair of nipples 28a, respectively, and pure water, for example, is supplied as a cooling fluid through the nipples 28a and the tubes 30a and flows into the cavity 9c. Further, a tube 30b is communicated with each of the pair of nipples 28b, and pure water supplied into the hollow portion 9c is discharged through the nipple 28b and the tube 30b. That is, the waveguide 9 is cooled by the cooling fluid flowing into the cavity 9c flowing in the cavity 9c.
[0049]
As shown in FIG. 2, the water supply side tube 30a branches off from the socket 33a, and guides pure water supplied from a water supply source through a thicker hose 34a. Further, the tube 30b on the drain side is gathered by a socket 33b, and the cooling fluid after use, in this case, pure water is drained through another thick hose 34b.
[0050]
In addition, you may make it the structure which pours the pure water discharged | emitted from the said cavity 9c in the said processing tank 3, without providing the said tube 30b by the side of drainage. In this case, the pure water poured into the treatment tank 3 is gradually discharged from the upper edge of the treatment tank 3 by a so-called overflow method. That is, since it is not necessary to provide other water supply facilities, the cost can be reduced.
[0051]
In the present embodiment, the hollow portion 9c has a height H ₀ of 6.0 mm in the traveling direction of ultrasonic vibration (the thickness H direction of the waveguide 9) and a direction orthogonal to the traveling direction of ultrasonic vibration ( The width W ₀ in the width W direction of the waveguide 9 is set to 36 mm. Further, the height H ₁ from the surface having the vibrator 7 which is the upper surface of the waveguide 9 to the upper end of the cavity 9c and the bottom of the waveguide 9 from the lower end of the cavity 9c. Each of the heights H ₂ up to the surface facing the upper surface is 23.5 mm.
[0052]
The height H ₁ and the height H ₂ are based on the sound velocity (5.15 × 10 ⁵ cm) of duralumin, which is the material of the waveguide body 9, as is the thickness H of the waveguide body 9. The half-wavelength λ / 2 (about 2.6 mm) of the ultrasonic vibration generated from the vibrator 7 calculated in this way is set to an approximately integral multiple, in this case, about 9 times, and is a resonance length.
[0053]
On the other hand, with respect to the height H _{0 of} the hollow portion 9c, that is, the dimension in the traveling direction of ultrasonic vibration (the thickness H direction of the waveguide 9), the cooling fluid flowing into the hollow portion 9c, In this case, it is approximately an integral multiple of the half wavelength λ / 2 of the ultrasonic vibration generated from the vibrator 7 calculated based on the sound speed of pure water, ideally just an integral multiple.
[0054]
Here, the half wavelength (λ / 2) of ultrasonic vibration based on the sound velocity of pure water is calculated by the following equation.
λ / 2 = C / 2f
However,
λ: one wavelength C: sound speed of pure water = 1.5 × 10 ⁵ cm
f: Frequency = 10 ⁶ Hz
Therefore, λ / 2 = 0.75 mm.
[0055]
That is, the height H ₀ of the hollow portion 9c is about 8 times the half wavelength (λ / 2) of ultrasonic vibration calculated based on the sound velocity of pure water, and is set to the resonance length. ing.
[0056]
In the present embodiment, the width W ₀ of the hollow portion 9c is about 48 times the half wavelength (λ / 2) of ultrasonic vibration based on the sound speed of pure water. At a high frequency, for example, a driving frequency of 1 MHz set in this embodiment, there is no adverse effect of the Poisson's ratio, i.e., no occurrence of lateral vibration. Therefore, the length L and the width W of the waveguide 9 Similarly, it can be arbitrarily set.
[0057]
Further, in this embodiment, the hollow portion 9c is formed in a flat rectangular parallelepiped, the two directions perpendicular to the traveling direction of the ultrasonic vibration, i.e., the width direction (the width W ₀ direction) and longitudinal (length L direction The parallelism in the width direction (width W ₀ direction) and the longitudinal direction (length L direction) of the cavity 9c with respect to the vibrator 7 is plus or minus. It is preferable to set it within about 3 degrees.
[0058]
Thus, by setting the dimension of the cavity 9c in the traveling direction of the ultrasonic vibration to the resonance length calculated from the sound velocity of the cooling fluid flowing in the cavity 9c, the inside of the waveguide 9 Even if the cavity 9c is formed in the waveguide 9 and the cooling fluid is present in the waveguide 9, the waveguide 9 resonates efficiently with the ultrasonic vibration generated by the vibrator 7, and the cleaning fluid Ultrasonic vibration can be applied to the.
[0059]
The cavity 9c is formed in a flat rectangular parallelepiped square hole and is perpendicular to the traveling direction of the ultrasonic vibration with respect to the vibrator 7, that is, in the width direction (width W ₀ direction). ) And the longitudinal direction (length L direction), the ultrasonic vibration generated by the vibrator 7 is not attenuated or reflected, and the ultrasonic vibration can be efficiently applied to the cleaning fluid. it can.
[0060]
In this embodiment, the hollow portion 9c is provided with only one flat rectangular parallelepiped-shaped square hole. However, the cooling in which the size of the ultrasonic vibration in the traveling direction flows into the hollow portion 9c. Set to the dimension of the resonance length calculated from the sound velocity of the working fluid and perpendicular to the traveling direction of the ultrasonic vibration with respect to the vibrator 7, that is, the width direction (width W ₀ direction) Further, a plurality of rectangular or cubic rectangular holes formed in parallel in the longitudinal direction (length L direction) may be provided.
[0061]
Further, the position where the hollow portion 9c is formed, that is, the height H ₁ from the surface of the waveguide 9 having the vibrator 7 to the upper end portion of the hollow portion 9c and the lower end portion of the hollow portion 9c If the height H ₂ to the surface facing the top surface, which is the bottom surface of the waveguide 9, is the resonance length of the ultrasonic vibration calculated based on the sound velocity of the material constituting the waveguide 9, It is variable as appropriate.
[0062]
The cooling means composed of the hollow portion 9c and the like is provided to heat the waveguide body 9 to a certain degree although it does not become high heat due to self-resonance of the waveguide body 9, By providing the waveguide 9 inside, the cooling effect on the waveguide 9 is high, and heat that adversely affects the vibrator 7 can be removed with high efficiency.
[0063]
Next, the vibrator 7 for exciting the waveguide 9 will be described.
[0064]
As apparent from FIG. 2, the length and width of the vibrator 7 are substantially equal to the length L and width W of the waveguide 9, and the thickness t is set to about 2 mm in this embodiment. Yes.
[0065]
The vibrator 7 includes a PZT (piezoelectric: piezoelectric) element 16, and electrode plates 17 and 18 attached to the entire upper and lower surfaces of the PZT element 16. The PZT element 16 and the upper electrode One of the corners of the plate 17 is cut away. In the cut portion, the lower electrode plate 18 is folded back on the upper side, that is, on the same plane as the electrode plate 17 with an arc-shaped gap 20 between the electrode plate 17 and the electrode portion 18a. It has become.
[0066]
Further, either one of the two power transmission wires 22a and 22b for applying a voltage of a predetermined drive frequency from the oscillator 12 (see FIG. 1) is a predetermined position of the electrode plate 17 and the electrode plate 18. Are connected to the electrode portion 18a.
[0067]
In the ultrasonic cleaning apparatus 10a according to the first embodiment of the present invention having the above-described configuration, the vibrator 7 is excited by a high frequency voltage applied from the oscillator 12, and ultrasonic vibration is generated. Then, the generated ultrasonic vibration is transmitted to the pure water 1 that is a cleaning fluid in the processing tank 3 through the waveguide body 9, and the object to be cleaned is immersed in the pure water 1, For example, a silicon wafer or the like is cleaned.
[0068]
The ultrasonic cleaning device 10a has the following effects, for example.
[0069]
{Circle around (1)} Like the conventional waveguide 105, the waveguide 9 provided in the ultrasonic excitation device of the present invention is set to have a large thickness H. ) Has a relatively large acoustic impedance. Therefore, when the pure water 1 as a cleaning fluid existing as an external load above the waveguide 9 is insufficient for some reason, and the liquid level 1a is lowered below the upper surface of the waveguide 9. However, it is possible to suppress the generation of heat by increasing the effective output as the vibration impedance of the vibrator 7 decreases due to the acoustic impedance of the entire apparatus, that is, the acoustic impedance of the entire apparatus decreases. That is, the adhesive that fixes the vibrator 7 to the waveguide 9 can be prevented from degrading and peeling, and the vibrator 7 itself can be prevented from cracking due to heat. Yes.
[0070]
(2) Since the cavity 9c is formed inside the waveguide 9 and has a configuration capable of supplying a cooling fluid such as pure water, the cooling effect on the waveguide 9 is high, Heat that adversely affects the vibrator 7 can be removed with high efficiency. The cavity 9c has a dimension in the traveling direction of ultrasonic vibration set to a resonance length calculated from the sound speed of a cooling fluid such as pure water flowing into the cavity 9c, and the vibrator 7 is a rectangular parallelepiped-shaped square hole parallel in two directions perpendicular to the traveling direction of the ultrasonic vibration, that is, in the width direction (width W ₀ direction) and the longitudinal direction (length L direction). From the above, the waveguide 9 efficiently resonates with the ultrasonic vibration generated by the vibrator 7, and does not attenuate or reflect the ultrasonic vibration generated by the vibrator 7. The ultrasonic vibration can be applied to the working fluid with high efficiency.
[0071]
(3) The cavity 9c, which is a cooling means for the waveguide 9, is formed inside the waveguide 9, and the outer peripheral surface 9a of the waveguide 9 is flush with the waveguide 9. The attachment site | part of the waveguide 9 and the said processing tank 3 is small, and the said ultrasonic cleaning apparatus 10a whole size reduction is possible. Moreover, even when it attaches to the washing tank of the same magnitude | size as the past, the effective volume in a washing tank can be enlarged.
[0072]
(4) Maintenance is extremely easy because there is no need to provide an interlocking facility consisting of sensors or the like in order to prevent flying.
[0073]
Next, as a second embodiment of the present invention, a nozzle shower type ultrasonic cleaning apparatus having the same effect as the first embodiment will be described with reference to FIGS.
[0074]
FIG. 3 is a side view including a partial cross section showing an ultrasonic cleaning apparatus as a second embodiment of the present invention, and FIG. 4 is a partial view showing an ultrasonic cleaning apparatus as a second embodiment of the present invention. It is a front view including a cross section. However, in FIG. 3 and FIG. 4, the same or corresponding components as those in the first embodiment are indicated using the same reference numerals. Further, in the following description, parts that are the same as those in the first embodiment will be omitted and only the main parts will be described.
[0075]
As shown in FIGS. 3 and 4, the ultrasonic cleaning apparatus 10 b according to the second embodiment of the present invention has the ultrasonic vibration generator 5 built in a cover 45. The cover 45 has an internal space separated into two upper and lower layers by a partition wall 45a, the vibrator 7 included in the ultrasonic vibration generator 5 is positioned on the upper layer 47 side, and the waveguide 9 is on the lower layer 48 side. Is located. The ultrasonic vibration generator 5 has the packing 14 interposed between the side portion 45c of the cover 45 and the inner edge 45d of the partition wall 45a and the outer peripheral surface 9a of the waveguide 9 over the entire circumference. The cover 45 is fixed in close contact with the cover 45. The packing 14 secures liquid-tightness on the upper layer 47 side, and acts as a vibration absorbing member. The packing 14 has an interface position, that is, an attachment position of the ultrasonic vibration generator 5 to the cover 45. In this case, is located above the hollow portion 9 c formed in the waveguide 9.
[0076]
A cleaning fluid, for example, the pure water 1 is continuously injected into the lower layer 48 through a socket 50 provided on a side of the cover 45, and the waveguide is guided to the injected pure water 1. Ultrasonic vibration is applied by the body 9.
[0077]
The pure water 1 to which ultrasonic vibration is applied is ejected in the direction of arrow F from the nozzle 45b of the cover 45 and supplied as a shower. The cover 45 including the nozzle 45b and a pump or the like (not shown) that continuously supplies the pure water 1 into the cover 45 are collectively referred to as a shower device.
[0078]
The ultrasonic cleaning apparatus 10b according to the second embodiment of the present invention is configured such that an object to be cleaned, for example, a silicon wafer is exposed to a shower ejected from the nozzle 45b and cleaned. Also in the ultrasonic cleaning apparatus 10b, the same effects as the ultrasonic cleaning apparatus 10a as the first embodiment of the present invention can be obtained.
[0079]
That is, for example,
{Circle around (1)} The thickness H of the waveguide 9 is set large, and the acoustic impedance of the waveguide 9 is relatively large that satisfies the equation (1). Therefore, when the supply amount of the pure water 1 as a cleaning fluid existing as an external load of the waveguide 9 is insufficient, the bubbles 53 accumulate along the lower surface of the waveguide 9, that is, along the vibration surface. Even in this case, heat generation due to an increase in effective output can be suppressed.
[0080]
(2) Since the hollow portion 9c as a cooling means is provided inside the waveguide body 9, the cooling effect on the waveguide body 9 is high, and heat that adversely affects the vibrator 7 is removed with high efficiency. be able to. The cavity 9c is parallel to the vibrator 7 in two directions perpendicular to the traveling direction of the ultrasonic vibration, that is, in the width direction (width W ₀ direction) and the longitudinal direction (length L direction). The transducer 7 is formed in a rectangular parallelepiped shape and has a resonance length calculated from the sound velocity of the cooling fluid flowing into the cavity 9c. The entire waveguide 9 including the cooling fluid in the cavity 9c resonates with the sonic vibration, and the ultrasonic vibration can be efficiently transmitted to the cleaning fluid.
[0081]
(3) Since the outer peripheral surface 9a of the waveguide body 9 is flush, the mounting portion between the waveguide body 9 and the cover 45 is small, and the entire ultrasonic cleaning apparatus 10b can be reduced in size. be able to.
[0082]
(4) Maintenance is extremely easy because there is no need to provide an interlock facility to prevent air blow.
The effects such as the above are achieved.
[0083]
Next, as a third embodiment of the present invention, an injection type ultrasonic excitation device will be described with reference to FIG.
[0084]
FIG. 5 is a side view including a partial cross section showing an injection type ultrasonic excitation apparatus as a third embodiment of the present invention. However, in FIG. 5, the same or corresponding components as those in the first and second embodiments are denoted by the same reference numerals. Further, in the following description, parts that are the same as those in the first embodiment and the second embodiment will be omitted, and the main parts will be described.
[0085]
As shown in FIG. 5, an ultrasonic excitation device 10c according to a third embodiment of the present invention includes a lower half of the ultrasonic vibration generating unit 5 including the vibrator 7 and the waveguide 9, that is, the vibration. A sealed case 55 is provided that surrounds the portion including the child 7 and maintains liquid tightness. The oscillation surface of the waveguide 9 is exposed to the outside of the sealed case 55. The ultrasonic excitation device 10c includes the ultrasonic vibration generating unit 5 including the sealed case 55, the oscillator 12 that applies a voltage having a predetermined frequency to the vibrator 7, and the cooling unit for the waveguide 9. It is comprised by.
[0086]
The ultrasonic excitation device 10c is configured to use the ultrasonic vibration generating unit 5 including the sealed case 55 by putting it in a cleaning fluid in the processing tank 3, for example, the pure water 1. . Then, a silicon wafer or the like as an object to be cleaned is immersed in the pure water 1 and cleaning is performed by exciting the pure water 1 by ultrasonic vibration transmitted by the waveguide 9.
[0087]
Also in the ultrasonic excitation device 10c as the third embodiment of the present invention, the same operational effects as those of the first and second embodiments can be obtained.
[0088]
That is, the acoustic impedance of the waveguide 9 is set to satisfy the equation (1), and even if the pure water 1 in the treatment tank 3 is almost absent, the effective output is increased. Since the heat generation can be suppressed and the waveguide 9 has the rectangular parallelepiped hollow portion 9c in which the dimension in the traveling direction of the ultrasonic vibration is set to the resonance length obtained from the sound velocity of the cooling fluid. The waveguide body 9 can efficiently remove heat associated with the resonance of the waveguide body 9 and includes the cooling fluid in the cavity 9c with respect to the ultrasonic vibration of the vibrator 7. The whole resonates, and ultrasonic vibrations can be efficiently transmitted to the cleaning fluid. In addition, since the outer peripheral surface 9a of the waveguide 9 is flush, the overall size of the ultrasonic excitation device 10c can be reduced, and the processing for introducing the ultrasonic vibration generator 5 is performed. The tank 3 is also effective in that it can be miniaturized.
[0089]
In each embodiment, pure water is used as the cooling fluid, but various fluids can be used as appropriate as long as the fluid is suitable for cooling and suitable for resonance with ultrasonic vibration. In each embodiment, pure water is used as the cleaning fluid, but various cleaning fluids can be used depending on the purpose of cleaning and the material of the object to be cleaned.
[0090]
In each of the embodiments, the waveguide 9 is formed in a rectangular parallelepiped shape. However, various shapes such as a disk shape can be adopted according to the shape of the space to be installed.
[0091]
【The invention's effect】
As described above, according to the ultrasonic excitation device of the present invention, it is possible to reliably suppress an increase in effective output even when the cleaning fluid is reduced, and to adversely affect the transmitted ultrasonic vibration such as attenuation. The size reduction can be achieved without giving Moreover, according to the ultrasonic cleaning apparatus of the present invention including the ultrasonic excitation apparatus, the entire apparatus can be reduced in size, and the space for installing the apparatus can be saved.
[Brief description of the drawings]
FIG. 1 is a side view including a partial cross section showing a cleaning tank type ultrasonic cleaning apparatus according to a first embodiment of the present invention.
FIG. 2 is a perspective view showing an ultrasonic vibration generator provided in the ultrasonic cleaning apparatus shown in FIG.
FIG. 3 is a side view including a partial cross section showing an ultrasonic cleaning apparatus as a second embodiment of the present invention.
FIG. 4 is a front view including a partial cross section showing an ultrasonic cleaning apparatus as a second embodiment of the present invention.
FIG. 5 is a side view including a partial cross section showing an injection type ultrasonic excitation apparatus as a third embodiment of the present invention.
FIG. 6 is a side view including a partial cross section showing a conventional ultrasonic cleaning apparatus.
7 is a perspective view showing a conventional ultrasonic vibration generator provided in the ultrasonic cleaning apparatus shown in FIG. 6. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pure water 1a Liquid level 3 Processing tank 3a Opening part 3b Inner edge 5 Ultrasonic vibration generation part (ultrasonic excitation apparatus)
7 vibrator (ultrasonic vibration generator)
9 Waveguide (Ultrasonic vibration generator)
9a Outer peripheral surface 9c Cavity 9d, 9e Lid 10a Ultrasonic cleaning device (first embodiment)
10b Ultrasonic cleaning device (second embodiment)
10c Ultrasonic cleaning device (third embodiment)
12 Oscillator (Ultrasonic excitation device)
14 Packing 16 PZT elements 17 and 18 Electrode plates 28a and 28b Nipple 30a and 30b Tube 45 Cover 45a Partition 45b Nozzle 45c Side 45d Inner edge 47 Upper layer 48 Lower layer 53 Foam 55 Sealed case

Claims (8)

A vibrator that generates ultrasonic vibrations of 200 kHz or higher;
A waveguide that is coupled to the vibrator and guides the ultrasonic vibration to an external load;
An ultrasonic excitation device having cooling means for cooling the waveguide,
The cooling means has a cavity formed inside the waveguide and into which a cooling fluid flows,
The dimension of the cavity in the traveling direction of the ultrasonic vibration is an integral multiple of a half wavelength of the ultrasonic vibration based on the sound velocity of the cooling fluid, and
The waveguide has a size from an upper surface having the vibrator to an upper end portion of the cavity and a size from a lower end of the cavity to a bottom surface facing the upper surface of the waveguide. An ultrasonic excitation device characterized by being an integral multiple of a half wavelength of the ultrasonic vibration based on the sound speed of the material. The super cavity according to claim 1, wherein the hollow portion has a rectangular parallelepiped shape or a cubic shape, and is formed parallel to the vibrator in two directions perpendicular to a traveling direction of the ultrasonic vibration. Sonic excitation device. The ultrasonic excitation device according to claim 1, wherein an outer peripheral surface of the waveguide is flush. 4. The ultrasonic excitation according to claim 1, wherein the waveguide is made of one material selected from duralumin, stainless steel, quartz, aluminum, an aluminum alloy, tantalum, and titanium. apparatus. The waveguide has a size that is an integral multiple of a half wavelength of the ultrasonic vibration based on a sound velocity of a material of the waveguide, and a dimension in a traveling direction of the ultrasonic vibration.
When the acoustic impedances of the vibrator, the waveguide, and the external load are Rma ₁ , Rma _2, and Rma ₃ , respectively, Rma ₁ <Rma ₂ <Rma ₃
The ultrasonic excitation device according to any one of claims 1 to 4, wherein: The ultrasonic excitation device according to claim 1, further comprising a sealed case surrounding the vibrator. An ultrasonic cleaning device comprising a treatment tank for storing a cleaning fluid and an ultrasonic excitation device for exciting the cleaning fluid,
The ultrasonic excitation device includes a vibrator that generates ultrasonic vibration of 200 kHz or more;
A waveguide that is coupled to the vibrator and guides the ultrasonic vibration to the cleaning fluid;
Cooling means for cooling the waveguide,
The cooling means has a cavity formed inside the waveguide and into which a cooling fluid flows,
The dimension of the cavity in the traveling direction of the ultrasonic vibration is an integral multiple of a half wavelength of the ultrasonic vibration based on the sound velocity of the cooling fluid, and
The waveguide has a size from an upper surface having the vibrator to an upper end portion of the cavity and a size from a lower end of the cavity to a bottom surface facing the upper surface of the waveguide. An ultrasonic cleaning apparatus characterized by being an integral multiple of a half wavelength of the ultrasonic vibration based on the sound speed of the material. The ultrasonic cleaning apparatus includes a shower apparatus having a nozzle for continuously supplying a cleaning fluid and ejecting the cleaning fluid, and an ultrasonic excitation apparatus for applying ultrasonic vibration to the cleaning fluid. And
The ultrasonic excitation device includes a vibrator that generates ultrasonic vibration of 200 kHz or more;
A waveguide that is coupled to the vibrator and guides the ultrasonic vibration to the cleaning fluid;
Cooling means for cooling the waveguide,
The cooling means has a cavity formed inside the waveguide and into which a cooling fluid flows,
The dimension of the cavity in the traveling direction of the ultrasonic vibration is an integral multiple of a half wavelength of the ultrasonic vibration based on the sound velocity of the cooling fluid, and
The waveguide has a size from an upper surface having the vibrator to an upper end portion of the cavity and a size from a lower end of the cavity to a bottom surface facing the upper surface of the waveguide. An ultrasonic cleaning apparatus characterized by being an integral multiple of a half wavelength of the ultrasonic vibration based on the sound speed of the material.

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